Harry Potter and the Witch's Secret
by JSmith25
Summary: With Voldemort defeated and the Zygons happily settled in the Lake, the Doctor has left Hogwarts for good. However, one question has yet to be answered: why can Tonks remember Umbridge? Read on to see how, when the Doctor inexplicably returns, the trio's world is turned upside down by the revelation of a horrifying secret. Sequel to Harry Potter and the Mystery of the Blue Box.
1. Deliberately Ridiculous

**Harry Potter and the Witch's Secret**

**Author Note: Hello, and welcome to the sequel to Harry Potter and the Mystery of the Blue Box! I know it's been a long time coming, but it's finally here! Before you begin the story, I recommend that you first read the Rewrite of Harry Potter and the Mystery of the Blue Box if you haven't already, as it contains plot elements that are essential to this story that weren't in the original. For those expecting a story similar to the last one, with action and mystery everywhere, be warned! Harry Potter and the Witch's Secret is a vastly different story, with lots and lots of angst, though things get a lot happier towards the end.****  
**

**Before we begin, a reminder that Harry, Ron and Hermione have just left with Professor Smith (the Doctor) in the TARDIS, and are currently travelling to adventures unknown...**

* * *

_"Many years ago, when I was in my Fifth Year at Hogwarts, I had a teacher called Professor Smith. He was, as you would say, a 'weirdo': his fashion sense was non-existant, and he very rarely said anything that made any sense, to me at least. But I couldn't help liking him, and by the end of the school year I treated him with a lot of respect, as I considered him to be the most intelligent and the bravest man alive._

_"He left after my Fifth Year, and I thought he'd gone for good, in fact, he even told me that himself. But we were wrong. Professor Smith did return, and when he did, he was a different man: selfish to the nth degree. He betrayed me, Ron and Hermione in the worst way possible: by revealing the witch's secret..._

Chapter 1 - Deliberately Ridiculous

Late June, 1996  
Ginny Weasley hummed quietly to herself as she walked down the seventh floor corridor, in the direction of the Gryffindor Common Room. She wanted to tell Hermione about her decision to start dating Dean Thomas, and to ask advice on how to break the news to her brother, Ron, who she was sure would react badly.

"Hermione?" Ginny called as she climbed through the portrait hole to the Gryffindor Common Room. "You in here?"

Receiving no answer from the empty room, Ginny walked up the stairs to the Fifth Year Girls' dormitory. After ascertaining that Hermione wasn't there either, Ginny turned to leave, but an old book lying open on Hermione's bed caught her eye. Curious, she walked over to Hermione's bed and picked it up. Hermione had left the book open at a page titled 'The Doctor'. Intrigued, Ginny began to read...

* * *

'_Perhaps the most famous encounter with the Doctor is the meeting described in the memoires of Godric Gryffindor. According to him, the Doctor and his three unknown, companions were instrumental in his choice of location and name for Hogwarts.'_

"So, lake," Professor Smith said cheerfully. "Great place for a school. And a swim. Or a swimming school. Though I think you guys would prefer a magic school, which is fair enough, I suppose, as you guys are wizards. Still, you never know when a school next to a lake could come in handy. I mean, it's very defensible. Cliffs on one side, lake next to cliffs, low land on other side, gives you a good view of the surrounding land. Should be enough to fight off anything."

The Founders looked at each other. They knew that magic in general was frowned upon by the rest of the world, or the 'muggles', as was the recently coined term. Having a defensible location for the school would be a great advantage if the 'muggles' ever found out about it.

Godric Gryffindor scratched his chin. "You certainly seem to know a lot about defences, Doctor," he said. "Would you care to join us in our efforts to build the mightiest wizarding school in all of England?"

"No, sorry, gotta go, things to do. These three are on holidays actually -"

Hermione coughed.

"Well, they're almost on holidays, same thing really. They've just finished their school year, they've only got one or two days to go."

"But they are wizards," Helga Hufflepuff said in surprise. "There are no school for wizards in the England, that is why we intend to build one!"

"We're from Hogwarts," Ron blurted out before he could stop himself.

"Hogwarts..." Rowena Ravenclaw mused. "I like that name..."

"Where is this Hogwarts?" Salazar Slytherin asked.

Harry, Ron and Hermione hesitated, not trusting themselves to speak. Luckily, Professor Smith came to their rescue.

"Oh, you know, it's around...somewhere," he said vaguely. "I wouldn't go looking for it, if I were you; it's about to be closed down."

He clapped his hands together. "Right then," he said. "We'd better be off! See you around...or not. I dunno, whenever. What about a thousand years? Sounds good, I'll visit again in a millennium...if I haven't already." He paused and looked at Harry, Ron and Hermione. "I have...never mind, then. Bye!"

He gave a cheery wave, then began walking back to the TARDIS.

"Uh, see you," Harry said, embarrassed, and he pulled on Ron's shirt. "Come on," he hissed.

But Ron seemed to be having an internal struggle within himself. He resisted both Harry and Hermione's attempts to pull him along with them until he finally burst out, "Can I have your autographs?"

The Founders looked at him, confused, as he pulled out a quill and some parchment from his robes.

"Err, just write your names on the parchment," Ron explained hurriedly.

Somewhat bemused, the Founders did so.

"Thanks!" Ron said breathlessly, before he turned and ran after Professor Smith, Harry and Hermione right behind him.

"What strange people," Rowena murmured. "Still...Hogwarts..."

Godric looked around at the surrounding countryside. "I think we shall do what the Doctor said, and build our school right here! Are we all in agreement?"

oOo

'_...the introduction of the Golden Snitch in Quidditch...'_

"Their brooms are so slow!" Ron moaned, as he watched the players float slowly past him on their way to the other end of the pitch. "A Cleansweep One is faster than the brooms these guys are using, and that's saying something.

Hermione rolled her eyes. "Just remember, Ronald, that we are in the Middle Ages. The technology for highspeed brooms doesn't exist yet!"

"Hmph," Ron muttered, and he folded his arms crossly.

Harry, on the other hand, was enjoying the match tremendously.

"This is great!" he exclaimed, grinning, as one team scored, causing several loud cheers to erupt from the spectators. "The game's barely changed at all!"

Hermione frowned. "Except for the horrid and completely unethical use of that poor little snidge," she said disapprovingly. "To even think of using the tiny bird as the object for the Seeker to catch..."

Suddenly, the crowd roared in anger as another person flew on to the field, completely disregarding the other players.

"Got it!" Professor Smith shouted triumphantly as he grabbed a tiny, winged golden ball. He looked around to see the players and spectators glaring at him crossly.

"Oh...sorry about interrupting your game!" he grinned, waving the ball at them. "It's just that I was testing a replacement I whipped up for those birds you use, the snidgets. Can I say that you guys are really lucky that animal welfare groups don't exist yet! They'd be all over you...figuratively. But anyway, I made a little ball, 'bout the same size as your normal Snidge. It flies, it's fast, and to top it off, it's programmed not to fly more than two miles from the pitch. I call it the Golden Snitch. Great name, isn't it?"

Harry and Ron looked at each other in horror.

"He didn't just invent the Snitch did he?" Harry said weakly as Professor Smith flew down to them, much to the relief of the payers, who quickly resumed the game.

"Just need to leave the blueprints with some bloke called Bowman Wright, then we're off!" Professor Smith said, dismounting and clapping a still-stunned Harry on the shoulder. "You know, I quite like Quidditch. Quidditch is cool!"

oOo

'_...met Nicolas Flamel...'_

"Where have you been, Professor?" Harry asked as they regrouped next to the TARDIS. They were in fourteenth century France, and Harry, Ron and Hermione had just spent the day wandering around the peaceful village and surrounding coutryside, relishing in the relaxing atmosphere.

"Oh, nowhere greatly interesting. Walked around the village until someone heard me say 'Doctor'. They got all excited, asked me if I knew anything about alchemy."

"Do you?" Hermione asked interestedly. "I've always wanted to know how to turn other metals into gold."

"That's easy," Professor Smith shrugged. "Use atomic fission or fusion. But anyway, this bloke was trying to make a stone of some sort - uh, immortality, I think. He was having a bit of trouble, so I helped him make it by giving him some spectrox that I found in the TARDIS."

"Spectrox? What's that?" said Ron.

"A substance that increases longevity. If you had enough of it, you could live forever. Blimey, that takes me back, they had a war on Androzani Minor over the stuff..."

Harry, Hermione and Ron glanced at each other.

"Professor," Hermione said cautiously. "What was the name of the person?"

Professor Smith frowned. "Nicholas Flamel, I think."

oOo

_'...involved with the creation of time turners...'_

The trio sat, bored, outside the conference room of the seventeenth century Ministry of Magic. They had been sitting for over an hour while Professor Smith negotiated the use of a rare substance he had - Taranium, he had called it.

"No, I don't have an extra supply. If you want more, you'll have to go to Uranus. Taranium isn't the rarest substance in the galaxy for a reason, you know! And since none of you know how to use it, goodbye!"

"Bloody hell, Professor Smith's cross!" Ron said in amazement. The next moment, footsteps could be heard, then the door to the conference room flung open, and Professor Smith stomped out.

"Come on," he said shortly, passing Ron, Hermione and Harry, who hastened after him.

"What's Taranium?" asked Harry, as they left the Ministry.

"Used in time travel," Professor Smith replied crossly. He rolled his eyes. "I told them it was rare, and that they didn't need much, but they go and use all of it in only two dozen!"

"Two dozen what?" said Ron.

"Time turners."

oOo

'_...the establishment of the International Statue of Wizarding Secrecy...'_

"What in Merlin's name possessed you to do that, Professor?" Harry groaned, covering his face with his hand.

"I just thought that the village would be a better place if everyone knew they had witches and wizards as neighbours!" Professor Smith protested. "They could all work together and have a better life!"

"But you didn't have to go and send a psychic message to a couple of young girls," Ron pointed out.

"And by doing so, start the Salem Witch Trials!" Hermione said furiously. "You've just caused the deaths twenty-five innocent witches and wizards, which is the primary factor that caused the establishment of the International Statue of Secrecy!"

Professor Smith had the decency to look guilty. "Sorry," he whispered, grimacing. "Though," he added, "thinking positively, at least we preserved history."

All three teenagers had to begrudgingly admit that he had a point.

oOo

'_Going even further back, it is said that the Doctor is the cause of lycanthropy, having appeared in Egypt at the same time the disease first emerged...'_

Harry staggered into the TARDIS, followed closely by Ron, Hermione and Professor Smith. They were covered from head to foot in dust, and were thoroughly sunburnt. A red fez sat on top of Professor Smith's head. Their clothes were in tatters, and they all looked very exhausted.

"Remind me to never go along with your decisions again, Professor," Ron said tiredly as he plonked himself on a seat next to the console.

"I didn't know that there was a Lupine-Wavelength Haemovariform infecting several members of Egypt's wizarding population, nor did I know it wanted to take over the world! I thought putting it in a rocket and sending it into space would be the best thing to do," Professor Smith said defensively.

Hermione glared at him. "Then the rocket exploded, spreading infected cells all over the planet thanks to air currents! We've just caused lycanthropy!"

Professor Smith winced. "Sorry," he said guiltily. "I'll try and land somewhere better next time.

"No," said Harry forcefully. "There won't be a next time. Just take us home, we've been away for over three weeks!"

"Oh, alright," Professor Smith said grumpily. "But we need to get changed first. Follow me!" he said, dashing down the stairs.

"Wait!" Hermione called. "Before we go back to Hogwarts, could I make a request?"

"Whatever you want," Professor Smith replied, and he grinned when Hermione told him her request. "Too easy," he said. "We'll do it as soon as we get changed."

* * *

An hour later, Hermione stood on the threshold of the TARDIS, staring out the open doors at the magnificent sight of the Milky Way galaxy. The humongous formation glowed with the brilliance of a million billion stars as it sat suspended in space. It was the most spectacular sigh she'd ever seen.

"I'm sorry, Professor," she murmured softly as she gazed down at her home galaxy. "I'm sorry for not believing you. Everything you said is true, everything. I just can't deny it."

She turned around to face Professor Smith, overcome with emotion from watching the galaxy hang in the empty black void of space. "Thank you," she said earnestly

"Don't mention it," Professor Smith said, waving a hand dismissively. "Right, home we go. Hogwarts, June, nineteen ninety-six!"

With a flourish, he pulled a lever, and the TARDIS immediately jerked into action. The doors swung shut before the familiar wheezing groaning sound began.

* * *

Thud!

The TARDIS' doors opened, and the trio exited and were greeted with the familiar sight of classroom six.

"Hey, look, we're back!" Ron said sarcastically.

"Of course, Mister Weasley. Why wouldn't we?!" Professor Smith asked, standing in the TARDIS' doorway, leaning casually against the frame.

Ron snorted. "As if. It took you five goes to get us to Egypt!"

Professor Smith pouted, but did not respond.

Hermione looked sadly around the classroom. "How are we going to go back to all of this?" she said. "After everwhere we've been, everything we've done...we won't ever be able to look at the wizarding world in the same way, not after having played such a role in shaping it."

Professor Smith shrugged. "You're human, you'll get over it," he said dismissively. "And you can always go look yourself up in a book or a museum. Like you said, we've played a big part in wizarding history, we're bound to be there somewhere."

"Oh!" Hermione cried softly. "The book!" She dashed out of the room without another word.

Silence. Then,

"You're leaving for good now, aren't you, Professor?" Harry asked.

Professor Smith nodded. "Yep. Still got plenty of things to do, most of which I'm late for. I'm done here, nothing more to do."

"But what about science!" Ron said. "You've got to teach that! Who'll do it if you go?"

"They'll find someone amazing," Professor Smith said unconcernedly. "Though tell Dumbledore that if he drops the subject, I _will_ come back. Fancy not knowing what gravity is!" he laughed.

"Well," he said, "time to go. Harry, good luck with getting rid of Mouldy-Wart. Ron, Harry's your friend, never desert him."

Harry and Ron nodded.

"Okay, then," Professor Smith said cheerfully. "Goodbye!"

He disappeared into the TARDIS and pulled the doors closed. A second later, the TARDIS shuddered, and the wheezing, groaning sound of its engines began. It slowly faded from sight, until finally, there was nothing left.

"D'you reckon he will come back?" Ron asked.

Harry shook his head. "Nah," he replied. "He's got other things to keep him occupied. What else could interest him here?"

* * *

**Author Note: And the sequel's underway! Not much of the trio travelling with the Doctor, I'm afraid, but if you liked the scene's that I wrote, and want more (whether new adventures or expanding on the ones shown here), I've put a poll up on my profile asking whether I should do a series of oneshots of the trio's adventures with the Doctor.**

**Updates (at this stage) will be posted every 4 to 7 days.**

**Replies to reviews (last chapter of rewrite of Mystery):**

**Miyu Hinamori: Not telling! You'll have to wait and find out. I agree, I might go back and do something about it at a later date. Harry coped well, on the whole. If I end up doing the oneshot series, I'll write the trio's first adventure with the Doctor.**

**Haven Wood: Thanks, and here it is! Yes, definitely. As the Doctor says, never ignore a coincidence, unless you're busy, in which case always ignore a coincidence. Yes, Tonks is most definitely awesome! I would imagine that Hermione would be furious if she encountered the enslaved Ood. I think she'd probably lose her faith in humanity too.**

** Insanityisgood25: No one said anything about marriage! ;) And I can say with 100% honesty that she's not Tonks! ****Thanks for the heads up, I've fixed them all now.**

**Wonderbee31: You won't find out who the woman is for a while, I'm afraid! And no, the trio won't be meeting any of the Doctor's past incarnations, unfortunately.**

**SuOmAlAiNeN92: Not saying! And there are no hints as to the woman's identity anywhere, be it on my profile or in the flashback sequence. The woman's identity is well shrouded in mystery!**

**I had decided that the big events of the books are fixed points, but I hadn't actually considered the notion that the TARDIS would make sure the Doctor was late in order to avoid them. The more I think about it, though, the more that makes sense, but I must admit that I prefer the idea of the Doctor piloting the TARDIS incorrectly. It's just so him!**


	2. Dreams

**Chapter 2 – Dreams**

14 July, 1996

_She stood in the middle of a battlefield, staring around at the uncountable corpses that littered the ground. Several were impaled by large pieces of debris, while others were mutilated beyond recognition. Hogwarts was in the distance in front of her, the astronomy tower collapsed, with several other spires on fire._

_A spell whizzed past her, and she reacted quickly, whirling around, her wand pointed at the person behind her. Her heart froze. It was her aunt, Bellatrix Lestrange._

_"Avada Kedavra!" Bellatrix cried, and a green bolt of energy burst from her wand, heading straight towards her._

_Luckily, her auror instincts kicked in, and she ducked, allowing the spell to go sailing over her head – only to collide with Sirius, who had appeared behind her._

_"No!" she yelled in anguish. Sirius Black, her cousin, had died because of her –_

_oOo_

Nymphadora Tonks' eyes flew open. She was soaked in sweat and breathing heavily. She had been having nightmares similar to the one she had just experienced semi-regularly for the past few months. All of them depicted the aftermath of the recent invasion at Hogwarts, or Sirius' fate in the Ministry, or both, and it was starting to unnerve her. Not just because they depicted scenes from events she'd rather forget, but because, whenever the dreams occurred, she felt scared, as if she wanted nothing else to do but drop her wand and run as far away as possible. This was strange, as she always looked forward to the rare fights that happened in her line of duty. She'd never wanted to run away from one before, usually she'd be running straight _to_ it!

Sighing, Tonks slipped out of bed and walked to the window. The dim glow of the early-morning sun was just visible above the many rooftops of suburban London. She groaned; she wouldn't be getting any more sleep this morning.

As she made herself a cup of tea, she begrudgingly admitted that she was having second thoughts about being an auror. To be fair, though, it wasn't the first time these thoughts had surfaced, as she'd been very hesitant when she initially got into the programme, and, even more recently, in the immediate aftermath of the catastrophe at Hogwarts. Now, several months later, after another horrific incident where her cousin had been killed...to be honest, she couldn't blame herself for wanting to give up her job as an auror in lieu of something less dangerous. But still, she'd been in dangerous situations before, so why should doubts begin to arise now? It just didn't make sense!

Tonks sipped her tea, mind churning. She didn't want to rush into a decision regarding her future as an auror. She'd give herself another couple of weeks to see if she could convince herself that she was living her dream. If she couldn't...then she'd have to find something else that interested her. For some reason, her dad's old sci-fi movies sounded appealing.

* * *

"I think you made the right decision, dear," Mrs Weasley said kindly, placing a steaming mug of tea in front of Tonks. It was a week and a half later, and Tonks had just made the heart-wrenching choice to leave the aurors . In a somewhat gloomy interview with Amelia Bones, she had conceded that her heart was no longer in the job, and that she wished to resign. Amelia had nodded understandingly, and said she didn't really blame her for making the decision. Nevertheless, Tonks couldn't help the tinge of regret that was floating around her stomach, but she knew she'd never be able to go back and rejoin.

"Thanks, Molly," she said glumly, sipping from the mug. To be brutally honest, it would be fair to say that after the horrible string of recent events, she was now thoroughly depressed, so much so that she was having trouble with her metamorph abilities, with her hair now messy, shoulder-length and mousy-brown.

"I always thought being an auror was dangerous," Mrs Weasley continued briskly, pottering round the Burrow's kitchen. "Always chasing after dark wizards, not knowing what you'd come up against...I don't know how people live with that amount of uncertainty in their lives. And now Ron wants to be one too, you know."

She glared reprovingly at Tonks, as if it was her fault that her youngest son wanted to have a dangerous job as a career.

Tonks sighed. "Relax, Molly, it's not all danger. Most of the time you're just sitting in a stuffy office all day making paper planes. If Ron wants do joinl that's fine, but I expect the training program will whip him into shape in no time." She gave a small smile. "And if the rationing on field training's anything to go by, I wouldn't expect him to last a month."

"Yes, that's true, I suppose, dear. It would be good for Ron to improve his table manners, not to mention his lacklustre work attitude that Ginny tells me he has...I just hope he did enough to pass his OWLs!" Mrs Wealsey said, wringing her hands anxiously.

"They'll be fine," Tonks replied sullenly, thinking back to when she had taken her NEWTs several years previously. While not the best student in her year, she was nevertheless in the top five, and had achieved either 'Exceeds Expectations' or 'Outstandings' in all her subjects, allowing her easy access into the auror programme. And what had it been for? Nothing, absolutely nothing.

"What am I going to do now?" she said. "Nothing interests me anymore except my dad's sci-fi movies for some reason."

"Movies? Those muggle moving pictures that Arthur keeps going on about? Well, why not try to get a job relating to them? If that's the only thing that takes your fancy at the moment, then why not go for it? Do a bit of job hunting, dear, to take your mind off things."

Someone knocked three times on the back door.

Mrs Weasley froze, and quickly whipped out her wand before walking cautiously to the door.

"Who's there?" she asked nervously. "Declare yourself!"

"It is I, Dumbledore, bringing Harry!"

Mrs Weasley's face broke into relief, and she put her wand away at once and opened the door. Dumbledore and Harry were standing on the threshold, waiting to be let in.

"Harry, dear!" Mrs Weasley exclaimed. "Gracious, Albus, you gave me a fright, you said not to expect you before morning!"

"We were lucky," said Dumbledore, ushering Harry over the threshold. "Slughorn proved much more persuadable than I had expected. Harry's doing, of course. Ah, hello, Nymphadora!"

Tonks groaned inwardly. How she hated that name! It was too long, ridiculous and made her think of a fairy whenever someone uttered it. If only her middle name had been sensible too, and she would have adopted that instead! Unfortunately, Fredrica was quite an unusual name too – though not on the same level as _Nymphadora_.

"Hello, Professor," she said. "Wotcher, Harry."

"Hello, Tonks," Harry replied.

'_At least he uses my last name,_' she thought grumpily, before draining the rest of the tea from her mug, standing up and wrapping her cloak around her shoulders.

"I'd better be off," she said. "Thanks for the tea and understanding, Molly."

"Please don't leave on my account," said Dumbledore courteously. "I cannot stay, I have urgent matters to discuss with Rufus Scrimgeour."

"No, no, I need to get going," said Tonks, not meeting Dumbledore's eyes. She wouldn't put it past him to use legilmancy on her, and she didn't want him to find out about her recent troubles – not yet, anyway. "Night -"

"Dear, why not come to dinner on the weekend, Remus and Mad-Eye are coming-?"

Tonks paused and considered. She'd prefer to be alone, but she did need to be distracted, and dinner at the Burrow would be a perfect opportunity to do so.

"Sure, Molly, I'll be there. Hopefully I'll have better news by then. Anyway...goodnight, everyone."

She hurried past Dumbledore and Harry into the yard; a few paces beyond the doorstep she turned on the spot, apparating away with a soft _crack_.

* * *

STAFF MEMBER NEEDED!

_Hogwarts School of Witchcraft and Wizardry has an available position in the following subject area:_

- _Science_

_Applicant must possess thorough knowledge and understsnding about various aspects of science, including chemistry, physics, biology and their respective branches._

_Send applications by owl to Hogwarts School of Witchcraft and Wizardry if interested and applicable. Applications must arrive at Hogwarts before August 15._

_oOo_

Tonks sighed and lowered the _Daily Prophet_. "I'm sorry, Molly, but I'm just not interested."

"Oh, come on, Tonks!" Ron said. "You'd be a great teacher!"

"I think you'd be more suited to Defence Against the Dark Arts," Ginny said thoughtfully. "Especially given your background as an auror."

"Look, dear," Mrs Weasley said kindly, setting a large roast pork on the table. They were having dinner outside, as the presence of Lupin and Mad-Eye that evening meant that the Burrow was very crowded indeed, and there was simply no room inside. "I asked Arthur what 'sci-fi' was, and he said it had something to do with fictional science. I couldn't help thinking of you when I saw the ad; I thought you ought to at least give it a try."

"But I don't even know half the things the job requires!" Tonks protested, leaning forward to grab several roast potatoes.

"I doubt anyone outside of the muggle world does, Tonks," Bill commented casually.

Lupin frowned. "Didn't you say that Ted watched the old muggle sci-fi shows? Surely you'd have some sort of advantage over the potential competition, if you're at least aware of what some of the concepts are. Personally, I wonder why the muggles bother with this sort of stuff at all."

"Ah, yes, well," Mr Weasley said importantly. "I believe it's because they're trying to satisfy their curiosity. Bless 'em, they're always asking questions."

"Are you sure it's not just because they're bored, dad?" Bill grinned.

Hermione pursed her lips as the Weasleys laughed. "Science is a very important part of muggle culture, thank you!" she huffed. "It tells them many things, like, for example, what everything in the universe is made up of."

"What do they reckon we're made up of, then?" Bill asked, intrigued.

"Well, um, lots of things," Hermione said hesitantly. "I'm not actually sure..."

Tonks rolled her eyes. "Humans and basically everything on the planet are carbon-based life forms, which means we primarily consist of the element Carbon. They've also conducted research into why we have certain skin colours, eye colours, hair colours and the like. They found that everything has DNA, which determines those traits."

Ron nodded. "DNA, I remember that, Professor Smith taught us that last year."

"So you do know some science stuff!" Ginny said in delight. "Great, you can come teach us after all!"

"But I don't know that much!" Tonks protested. "I've just picked up bits and pieces..."

"You could always research in a library," Harry suggested.

Tonks stared around the table. Harry, Ron, Hermione and Ginny were looking at her eagerly, while the other adults observed the situation in amusement. She groaned. She'd have to do it, otherwise she'd be forced to, and she had never liked being coerced into action. As much as she said she didn't know that much about science, she _had _paid attention to the programmes her dad was watching, and actually knew quite a bit more than she was letting on. Oh, not the advanced stuff, only the basics, really, but as much as she hated to admit it, she had always been a fast learner, so Harry's suggestion of going to a library wasn't out of the question either.

She opened her mouth, then paused, quickly coming to a decision.

"You win," she said eventually. "I'll do some research, look into it a bit. No promises though."

Mrs Weasley beamed. "That's very sensible of you dear; goodness knows you need something to take your mind off...oh, never mind. I'm sure you'll be an excellent teacher!"

Tonks' heart sank. So that was why Mrs Weasley was so keen for her to become a teacher – as a distraction from Sirius' death. She sighed. Her cousin's death was only part of the reason for her current depressed state, the other, of course, being her dreams.

"It's not that, Molly, it's...other stuff as well," she said.

"Such as?" Mrs Weasley asked.

"You know, stuff," Tonks said evasively. She didn't really want to share the dreams just yet – she'd wait for several more months, just to see if they would fade in time as per usual.

* * *

"Dora!" Ted Tonks cried when he opened the front door an hour later. He moved forward and wrapped his daughter in a big hug. "It's great to see you, come in, come in! Andromeda, Dora's here!" he called, as Tonks moved past him and into the living room, tripping on the carpet in the process.

Andromeda came bustling in from the hallway just in time to hear Tonks curse loudly.

"Nymphadora, watch that language!" she said sternly, before hurrying to hug her daughter as well. "Now, to what do we owe the pleasure of your visit?"

Tonks plonked herself down on an extremely comfortable sofa. "Well...I'm no longer an auror," she mumbled imperceptibly.

"Hmm, what's that?" Ted asked as he and Andromeda sat down opposite Tonks.

"I'm, err, not an auror anymore," Tonks repeated, looking determinedly at the floor in an attempt to avoid seeing her parents' reactions. "I resigned."

"Oh, dear, why?" Andromeda asked softly. "You've wanted to be an auror for five years!"

Tonks looked up sharply, frowning. "I've wanted to be an auror all my life, not just for five years!" she snapped.

"Yes, sorry, that's what I meant," Andromeda corrected hastily.

Ted smiled sadly. "Why did you give it up, honey? It was your dream."

Tonks stiffened involuntarily. Surely her dad didn't know about her dreams? No, it must have been a coincidence.

"Um, got bored, I supposed," she lied, hoping it was enough to deceive her parents. The looks they exchanged, however, told her that they knew something was amiss. Thankfull, though, they decided to drop the subject.

"Well, if that's the case, then," Andromeda said slowly. "I suppose that's fine. Have you worked out what you're going to do now?"

Tonks wiped her face with her hands. "Well...I've been getting this feeling that I should be doing something with science, of all things." She looked at her dad. "I think your obsession with science-fiction is affecting me," she joked, momentarily forgetting her worry and depression about her dreams and the big life-changing events.

Ted beamed. "I knew this would happen, Dora!" he said happily. "I've been waiting for your interest in science to bloom into something more! Where are you going to work? The muggle world, I suppose, I can't imagine that many people in the wizarding world care much about science."

"Well actually," Tonks said. "There's a position at Hogwarts that I've been...forced to at least look into." She scowled.

"Hogwarts?" Andromeda said in disbelief. "What does Hogwarts care about your father's hobby for?"

"Didn't you read the paper on Saturday?"

Ted and Andromeda shook their heads.

"We were out camping," Andromeda explained.

"Hope you two had fun," Tonks said, grinning slightly. "Anyway, Hogwarts needs a new science teacher after the old one practically ran away after recent...events."

"They had a science subject last year?" Ted cried. "Why wasn't I told!"

Andromeda laughed. "You can complain about the injustices of the world later, dear," she said. "But for now, I think we should congratulate Nymphadora for applying to be a teacher at Hogwarts."

Tonks grit her teeth at the use of her full name, but restrained herself from showing any other reaction. Instead, she said, "I haven't applied for it yet, mum, and I probably won't either. The job description said applicants need to know a lot about physics, chemistry and biology, and I only know the basics from watching dad's movies!"

"But you've always been an excellent reader and learner, surely you could -"

"I wouldn't know where to start!" Tonks protested. "There's so much stuff to know and understand!"

Ted coughed. "I believe I can help there," he said. He stood up and walked over to the living room bookshelf. He took several thick volumes off the shelves and returned to his seat.

"There you go," he said, grinning as he handed the books to his dumbfounded daughter. "I've had these for ages - they have about everything you need to know about science, plus it's easy to understand. You'll have finished them in no time!"

Tonks looked at her father in amazement. "Why do you have all these?" she asked incredulously. "I thought you only liked sci-fi, not science!"

Ted shrugged. "I've been interested in proper science for ages, about five years, I think, just after you left home. You've never been around enough to notice."

"Hold on..." Tonks frowned, pausing in her perusal of one of the books. "Quantum Mechanics? Sub-atomic theory with baryons and mesons? How am I meant to understand all this by the time I get to Hogwarts, plus everything else?"

"I don't think you'll need to know everything immediately," Andromeda said reassuringly. "Just make sure you know enough to get then learn the rest as you go. At Hogwarts."

"But I haven't even decided whether or not I'm going for the job yet!" Tonks protested.

"Now, none of that nonsense, young lady!" Andromeda said. "I think we all know that you're going to apply, and that you will get the job."

Tonks knew that her mother was right. She would go for the interview, because she needed a job, and this was one that she had to admit she would probably enjoy. She knew that she'd get the job, too, because she was too good at nearly everything she did. How she hated life sometimes!

* * *

_She whirled around, only to see, much to her horror, that Bellatrix Lestrange was standing right behind her. _

_Bellatrix raised her wand threateningly. "Alternative function?" she said. "There must be a second circuit in there somewhere."_

oOo

"What. The. Hell," said Tonks as soon as she woke up. What the hell had her aunt said in her dream? Something about alternative functions? Alternative functions of what? And there was something about second circuits as well...but witches like Bellatrix wouldn't have a clue what a circuit was, let alone how to use it in a sentence, so what her dream-aunt had said was completely nonsensical.

She frowned. Were the odd words uttered by her dream-aunt evidence of something more worrying? Was it possible that she was going mad? No, of course not, but she couldn't deny that it was strange. Still, nothing to be concerned about. Chance was that it would never happen again, that it was only a one-off occurence. It was one of the many unsolved mysteries regarding dreams, and she shouldn't waste anymore time worrying over something so unimportant. Better to read her dad's science books than dwell on dreams. After all, dreams were harmless. Weren't they?

* * *

**Author Note: Importantish chapter, this one, as it sets up where Tonks will be for the rest of the story: at Hogwarts. I hope her resigning as an auror isn't hard to accept, especially with the background I've given her. It's a radical decision, I know, but one that needed to be made in the grand scheme of things.**

**Replies to reviews:**

**MrsDalek: Yep, it sure is! I hope it lives up to your expectations. **

**Insanidtyisgood25: This won't be the biggest angst story in the world, but it does contain a bit. I could compare the angst levels to those present in a particular Doctor Who epsiode, but doing so would kind of be spoilers, so I won't. I think you'll be able to cope with it, though. And the story does have a mystery: all the questions about Tonks will be answered, but how? Oh, and humour is defintely present as well. :)**

**Thanks!**

**Wonderbee31: After the events of Mystery of the Blue Box, the only Death Eaters Voldemort has left are (essentially) the members of his inner circle. It's not really focused on in the story, but he uses new tactics, such as subterfuge, to achieve his ends. The Doctor taught him a well needed lesson! And remember, Voldemort wants to know how to regenerate (which he thinks means he'll be able to live forever), so keep that in mind...**

**Ailavyn Siniyash: That's an interesting theory, but one that seems to be prevalent for a few people, I've found. Don't know why, really, I think it must be wishful thinking! Unfortunately though, no old (or new) Time Lords will be introduced in the story. Thanks!**

**SuOmAlAiNeN92: Yeah, the previous chapter was meant to be a cross between that scene from The Power of Three (7 weeks sounds right) and the opening sequence from The Impossible Astronaut, where the Doctor is 'deliberately ridiculous' in history in an attempt to get Amy and Rory's attention.**

**When the sequel was initially conceptualised, Harry, Ron and Hermione would indeed remain with the Doctor for the whole story, which was going to be adventure in Egypt that resulted in the creation of lycanthropy (this survived in watered down form as a scene in the previous chapter). I only dumped the idea when I had an amazing idea that lead to the current plot of the story.**

**The trio will be in the story a lot, actually, so I suppose you could count them as companions if you wanted, although the term should be applied much more loosely than it was in the previous story. And I didn't say Tonks would be the companion either! ;) And yep, I've tried to keep her characterisation as faithful as possible to book 6.**

**Haven Wood: I think I'll probably end up doing it - though not until after this story is finished. Thanks!**


	3. Breaking the Uncertainty Principle

Chapter 3 - Breaking the Uncertainty Principle  


Unfortunately for Tonks, her weird dream with Bellatrix talking nonsense was not a one-off occurence. The dream popped up once every week at a minimum, and it was becoming worrying, especially as, several weeks later, it should have faded by now. But nope, it would happen: she would be standing in Hogwarts' grounds, then Bellatrix would appear and say something about circuits.

Tonks had racked her brains in an attempt to determine what had caused her brain to dream of Bellatrix talking about muggle things in a completely normal tone, but she couldn't think of anything that could be the cause. It was as if her brain had just invented it on the spot! Still, she assured herself that she would find the source of her strange dreams, even if it took her all year.

Her auror training had made her a very stubborn person.

* * *

_Miss Nymphadora Tonks,_

_ I am delighted to inform you that your application for the position of Science Professor at Hogwarts School of Witchcraft and Wizardry was successful. However, before a candidate is appointed, a series of interviews is conducted by the Headmaster. Your interview has been scheduled for August 23 at 11 o'clock. If personal circumstances mean this time and date is not suitable, please owl us an alternative no later than twenty-four hours before the appointed interview time._

_Yours sincerely,_

_Professor M. McGonagall, Deputy Headmistress_

oOo

Mrs Weasley looked up at Tonks, beaming. "Well done, dear!" she said happily, handing the letter back to Tonks.

"Thanks, Molly," Tonks said.

"You'll get the job, I know you will," Ginny said excitedly. "You'll blow all the other candidates out of the water."

"Now, Ginny, don't give Tonks false hope. For all she knows, there could be someone else far more knowledgeable than she is."

Ginny snorted. "Please. The only other people who are going to go for the job are muggleborns, and how many of them are going to have dads with books that have everything there is to know about science in them?" She turned to Tonks. "Seriously, all you need to do is explain quantum whatsis to Dumbledore, and he'll hire you on the spot."

"If I don't overheat his brain," Tonks joked, causing Ron to choke on his bacon.

"Overheat...overheat _Dumbledore_'s brain?" he said in astonishment. "Is that even possible?"

Tonks grinned evilly. "If you knew what quantum mechanics is, Ron, you would agree with me. Would you like me to explain it to you?"

"Err, no thanks," Ron said hastily.

"Why not? It's easy to understand...well, for me, I suppose."

It was true. Much to her great surprise, even the 'hardest' of the muggle sciences was relatively simple to her. She didn't know why, but phenomena like the wave-particle duality, the Heisenberg Uncertainty Principle, and Quantum Entanglement just made sense to her. It was like she didn't even need to attempt to understand them, she read the words and the information went straight to her brain and was immediately absorbed and comprehended. If Tonks didn't know better, she'd swear that the sensation was rather like rediscovering old memories that had been locked away, inaccessible. But that was impossible, as she'd never even heard of quantum mechanics before, let alone read any literature on the subject. The more she thought about it, though, the more she realised that this sensation had applied to most, if not all, of the other branches of science in her dad's book as well. And that was scary. She _knew_ that she hadn't come across the information before, but at the same time, it felt familiar, and yet...incomplete. As if, just out of her reach, there was the solution to Heisenberg's Uncertainty Principle, a way to determine _both_ the momentum and location of an electron in an atom; it was as if she knew why electrons had mass, when the question had puzzled muggle scientists for decades.

"Yeah, but that's you," said Harry. "You're an auror. You're trained to understand stuff."

Tonks shrugged. "That's true, I suppose, but Mister curse-breaker over there is better qualified to 'understand stuff' than I am."

She pointed at Bill, who was sitting a fair way down the table, being fed food by Fleur.

"Curse breaking's all about analysis," he explained, seeing everyone's questioning looks. "In order to successully break the curse, I have to know and understand how the curse was placed, when, and for what purpose. Then again," he said, holding up a hand to stop Fleur from delivering a piece of pie to his mouth, "from what I've heard about this science stuff, even that would be way over my head!"

"I'm not so sure," Hermione huffed. "All this quantum mechanics stuff doesn't sound so hard. I've done some research at my local library over the holidays, so I know a lot more about science, particularly physics, now."

"Why didn't you just research quantum mechanics then?" Harry asked.

"Ran out of time before I came here."

Fred nudged Tonks. "Show her who's boss with science, Tonksie!" he whispered.

Tonks smirked. "Gotcha. Hermione?" she asked. "You say quantum mechanics isn't hard? Could you then please explain how a photon can be in two places at once?"

Hermione frowned. "Sorry?"

"How can a photon be in two places at once?"

"It can't, it's impossible."

"Is it? Quantum mechanics disagrees."

"But that's just absurd! How on earth could a particle possibly be in two places at one? That just goes against all the logic in the universe!" She stared around the table in anguish, only to see that everyone save Mrs Weasley and Fleur were desperately trying to stop themselves from laughing. "Oh, alright, I admit it, I got myself worked up about nothing," she sighed, realising that she had just been had. "Good one," she said to Tonks. "You fooled me for a few seconds."

At this, Tonks did burst out laughing. "That's just it, 'Mione," she said. "It's the truth. A photon _can_ be in two places at once!" She continued sniggering while Hermione folded her arms and glared up at the sky.

It was at this moment that a curious thing happened. Tonks was still laughing, but as she did so, her hair slowly turned from its mousy-brown, depressed state back into its normal, shoulder length, dark purple style.

"Hey, your hair's purple again!" Ron blurted out, noticing the change almost immediately.

Tonks stopped laughing at once. "Rubbish. I haven't been able to metamorph for ages."

"He's right, Tonks," said Harry, nodding at her head. "It's back to normal."

Tonks quickly grabbed a few loose strands and brought them in front of her face. To her great delight, they were indeed purple. "Finally!" she breathed in relief, sinking back in her chair.

"This is excellent, dear," Mrs Weasley said kindly. "It's good to know that you've finally gotten over -"

"The Ministry?" Tonks sighed exasperatedly. "Molly, I don't know where you got the idea that my mental health was ruined by the Ministry, because it hasn't. I've been worrying about...other things long before the Ministry happened.

"But I thought, after you came to see me that night..."

"I was more upset about my decision to quit, Molly. Yes, the Ministry may have contributed towards the decision, but it was hardly the major cause. I'd been having doubts long before then."

Mrs Weasley opened her mouth to respond, but Mr Weasley put a hand on her shoulder.

"Relax, Molly," he said. "Tonks is an adult, she can run her own life."

Mrs Weasley pursed her lips, but nodded.

Harry, Ron, Hermione, Fred, George and Ginny exchanged looks. While Tonks had explicitly stated it, it wasn't hard to realise that her doubts had begun sometime during or after the catastrophe at Hogwarts. Anyone who had experienced it would be scarred for live, just as they were. They may not show it, but they all knew the events of those days would be with them for the rest of their lives. And after what had happened to her fellow aurors, they couldn't blame Tonks for wanting to quit.

* * *

Albus Dumbledore sat quietly in his office, listening to the quiet whirring of his many silver machines. It was August 23, and he was expecting Nymphadora Tonks to knock on his door any second. To be completely honest, he was rather surprised that Nymphadora applied for the job, as he thought she was still an auror. He'd investigated that curiosity, and found that she had quit some weeks earlier. Although he wished she hadn't made such a decision, it wasn't his place to interfere with her life and tell her that she need to rejoin. No, he would fully support her in her decision to apply for the job of Science Professor.

_Knock knock._

Dumbledore shifted slightly in his chair. "Come in."

The door opened, and Tonks walked in, looking slightly nervous.

"Ah, Nymphadora," said Dumbledore. "Please, take a seat."

Tonks obliged and sat down, looking around at the many portraits that lined the walls.

"Now, I am of the understanding that you wish to become the Science Professor at Hogwarts," Dumbledore said, eyes twinkling over his half-moon glasses. "I am very glad to hear that. I am sure that, if you succeed in your application, you will become a very successful and popular teacher. However, for occasions such as this, one cannot pick a candidate on a whim. Duty tells me that I must ask for any qualifications you may have that make you a suitable person for the post."

"I, err, don't have any, Professor, apart from my NEWTs and auror qualifications," Tonks replied, trying not to look to anxious. She hadn't realised that she'd need qualifications for the job, as science was...obscure in the wizarding world, to say the least. She had been under the impression that there hadn't been any qualifications that would deem a person suitable to teach science.

"Naturally, naturally," Dumbledore said cheerfully. "However, I think those should be sufficient. Professor John Smith , the former teacher, left a note last year which simply said that I should pick a candidate only if they could, without hesitating, explain the theory behind Schrödinger's cat. So, when you're ready."

"Oh, right," Tonks said. Quickly recalling everything she knew about Schrödinger's cat and condensing it to explain the theory behind it, she began. "Schrödinger's cat is an analogy used to explain quantum superposition. The analogy goes that if a cat is put in an inescapable room with a bomb that has a fifty percent chance to explode in the next minute, we won't know whether the cat alive or dead after that minute until we open the door to the room and look in. During the minute that we wait, for all intents and purposes, the cat is both alive and dead at the same time, but when we open the door, the cat is _either_ alive or dead, not both. Us opening the door forces nature to make a decision as to whether the cat is alive or dead. Our own observation of the experiment determines its outcome."

Dumbledore looked down at the explanation Professor Smith had provided for his benefit. It contained everything Nymphadora had said, plus a bit more, something about Erwin Schrödinger being 'a nice guy' who 'hated cats', before it quickly dissolved into scientific ramblings about things Dumbledore didn't understand. One thing was certain, though: out of all the people he had interviewed so far, Tonks had explained the theory behind this strange scientific cat the best, at least according to the explanation Professor Smith had given him. But did this mean she was the ideal person for the job, as Professor Smith wanted? No. He couldn't make that decision yet, as he still had a few more people to interview before he made a final choice.

"Nymphadora," he began, ignoring the momentary scowl that crossed Tonks' face at the use of her first name, "you will be delighted to know that everything you have said was in the template Professor Smith provided. I would also like to add that you have given the best explanation of Schrödinger's cat so far. "

Tonks crossed her fingers under the table.

"Unfortunately, as much as I would like to hire you right here and now, courtesy dictates that I also interview the remaining candidates. Rest assured, however, that if no other explanations are as good as yours, you will be the first person I choose."

Tonks' heart soared. She had essentially been given the job! Soon, in just a few weeks, she'd be teaching all areas of science to a whole new generation.

"Great!" she said, beaming. "Let me know when you need me."

Dumbledore nodded. "I will. Now, perhaps you'd like to stay and talk? Your visit here need not be completely because of formal purposes."

"No, sorry, bit busy, things to do. I've got a book that I need to take back to my dad, actually."

"Of course. Thank you for coming, Nymphadora."

The two shook hands, and Tonks quickly left the room, tripping on the carpet in the process.

* * *

"Thanks for the book, dad."

"Don't worry about it, Dora," Ted replied, taking the book from his daughter. "I've got a few more there on the bookshelf if you want to have a look at them."

"Yeah, I'll take a look," Tonks said, and she walked over to the bookshelf, removed a volume, and flipped through the pages. "Come on, dad," she said. "This one's all theoretical. You can't break Heisenberg's Uncertainty Principle!"

Ted looked indignant. "Yes you can, I do it all the time!" he huffed, before he wacked the side of his head. "I mean, you're right, we can't. But that might not be true in the future."

Tonks frowned. "You alright, dad?" she asked.

Ted sighed and sat down. "Yes, Dora, I'm fine. I'm just getting a bit tired, you know. One doesn't exist in twelve dimensions without straining oneself in four, you know."

"What?"

Ted gave her a small smile. "Just a little string theory joke, Dora, nothing else."

Tonks plonked herself down next to him. "What's up, dad?" she said worriedly. "Something's wrong."

Ted stared off into space. "Your life is going to change soon, Dora," he said vacantly.

"What do you mean?"

"You'll get that job at Hogwarts, and life will never be the same again. You'll be a different person by the end of it. You won't be my little Dora anymore, you'll be my Saviour again."

* * *

Tonks left her parents' house half an hour later feeling rather worried. Her dad had been acting very strangely, and she wasn't sure why. She could understand the string theory joke, that was very much him, but what was that about him saying he broke Heisenberg's Uncertainty Principle all the time? It wasn't physically possible; muggles had been trying to do it for years! But even if he could, what would it let him achieve? All he would be able to is know the momentum and location of an electron at a certain point in time...but for what?

She shook her head, it just didn't make sense, just like nearly everything else in her life at the moment.

* * *

_She was standing at the head of a class, clearly teaching them something. Their young, eager faces stared up at her, ready to learn._

_"Wotcher," she said, "Today, we're going to learn how to break Heisenberg's Uncertainty Principle, just like my dad does all the time. Now, can anyone tell me what Heisenberg's Uncertainty Principal is?"_

_A blonde girl, whom she vaguely recognised as being a friend of Ginny's, raised her hand._

_"Yes?"_

_"Without a field interface stabiliser, you can't cross from one to the other," the girl said matter-of-factly._

_She nodded. "Excellent answer."_

* * *

**Author Note: This chapter took ages to write, mainly because I was itching to get into the meat of the story, where things are much more exciting. Unfortunately, though, all this setting up stuff is important! There's quite a bit of foreshadowing done in this chapter! And yes, I know that Tonks' hair is meant to be pink, but I prefer the dark purple from the movies, so that's what I'm sticking with.  
**

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**SuOmAlAiNeN92: Actually, all of Tonks' interactions with the Doctor take place at Hogwarts. **

**Bright Eyes Illusionist: Thanks! I think she does too, and the Doctor agrees (will agree).**


	4. Back to Hogwarts

Chapter 4 - Back to Hogwarts

Tonks spent the next few days eagerly waiting to be contacted by Dumbledore, in the hope that she had indeed been the best candidate for Science Professor at Hogwarts. Having returned her dad's book, she spent her time visiting the local library and researching some of the more recent developments in the science world by reading the latest issues of scientific journals. To her surprise, though, she rarely came across anything she didn't already know; it seemed that her dad's book had most of the information muggles already knew. She did find it curious, however, that an old book her dad had bought several years ago had some of the latest scientific discoveries, such as the confirmation of the existence of yet another element, Ununbium. Still, she shrugged it off, assuming that the publishers of the book had simply known about the confirmation before it was publically announced. After all, these sorts of things took years before becoming public knowledge. Still, it was intriguing that the book should have _that_ information, when it had nothing on other new developments. She might have to ask her dad about that later, if she had the time before she (hopefully) left for Hogwarts.

On the last day of August, however, Tonks was very much doubting that she'd got the job, mainly because of the lateness of the hour - term started tomorrow! Surely, if she hadn't got the job she would have received a letter notifying her of the fact? But no, she'd had no communication with Hogwarts, or Professor Dumbledore, for a week. But, as her dad always said, no news is good news.

As if reading her thoughts, her fireplace suddenly lit up, bright emerald flames roaring into life. A figure appeared in the flames, spinning rapidly, before coming to a halt, brushing the soot of his robes and stepping into her flats living room. It was Dumbledore.

"Ah, Nymphadora!" he said, beaming at her surprised face. "I hope I haven't interrupted anything?"

Quickly recovering from her surprise at the abrupt arrival of the Headmaster, Tonks shook her head. "No, nothing," she said. "I wasn't doing much, really." What was Dumbledore here for? Could it be...?

"Excellent," said Dumbledore, nodding approvingly. "Now, down to business. I am delighted to inform you that I am here to offer you the post of Science Professor at Hogwarts School of Witchcraft and Wizardry. Do you accept my offer?"

Tonks released the breath she hadn't even realised she had been holding. "Yes, course I will," she grinned.

"I thought as much," Dumbledore said, his eyes twinkling. "My apologies for the short notice, but there were quite a few interviews I needed to get through, and everything needed to be confirmed with the rest of the staff, and of course, the Ministry. Now, I'm sure you know that term starts tomorrow, so I'm confident that you'll be spending the rest of the day packing! You'll catch the train, I imagine? Good. Well then, I'll see you tomorrow at the Welcoming Feast!"

And with that, Dumbledore threw some floo powder on the fireplace, stepped into it, and disappeared in a whirl of green flames.

Tonks surveyed her flat, smiling broadly. '_Right,_' she thought. '_Let's get packing!_'

* * *

The next day, Tonks sat in a compartment in the very last carriage in the Hogwarts Express, wondering if Harry, Ron, Hermione or Ginny would stumble across her. She grinned mischievously. She liked surprises, and her favourite students would be getting one if they saw her on the train. And if they didn't, it wouldn't matter either, as she'd be sitting up at the staff table for the duration of the feast, not to mention that Dumbledore would be introducing her to the whole school.

As the train began to leave platform 9 and three quarters, she mentally ran through everything she'd needed to pack. Satisfied that she'd remembered everything, she gazed out the window as the buildings of London sped past.

Several minutes later, she heard voices echoing down the corridor.

"They're staring at you because you were at the Ministry too," someone was saying. "Our little adventure there was all over the Daily Prophet, you must've seen it."

A moment later, Harry appeared outside the compartment, followed closely by two people she recognised as Ginny's friend Luna and the Longbottom boy who had been at the Ministry with Harry – the event they'd just been discussing. Not wanting all three students to recognise her immediately, Tonks quickly used her metamorph powers to age herself several decades. She was reasonably sure that the students – Harry in particular – wouldn't pick up on her little trick.

Harry's head popped through the compartment door. "Excuse me," he said. "Would it be alright if we sat here? Everywhere else is full."

"Certainly, young man," Tonks said, faking a wavering, elderly voice.

Harry, Luna and the Longbottom boy (Neville, wasn't it?) entered and heaved their trunks onto the luggage rack, then sat down.

"Hello, Tonks," Luna said dreamily. Harry and Neville looked at her in surprise.

"What d'you mean? That's not Tonks!" Harry said.

"Of course it is," Luna continued."She's just used her metamorph powers to make herself appear older."

"Damn," Tonks swore, and she resumed her usual form.

The looks on Harry and Neville's faces were priceless.

"But – what – how?" blubbered Neville.

"What're you doing here?" asked Harry.

Tonks simply grinned. "I got the job," she said happily.

"Great!" Harry enthused. "I knew you'd get it!"

Tonks shrugged modestly and turned to Neville. "I'm a metamorphagus," she explained, answering his questions. "I can change my appearance at will."

Neville frowned. "Then how did Luna recognise you? She's only seen you once, at the Ministry!"

"Her clothes," Luna said simply. "They're the same style that she was wearing at the Ministry. And the eyes, the eyes were the same, changing from green to blue, back to green, then to brown before repeating endlessly."

"My eyes don't change colour!" Tonks protested. "I've been looking at them in the mirror for twenty-three years!"

"Not to you," Luna said mysteriously. "But they do to me."

Tonks, Harry and Neville exchanged glances. While Harry was used to Luna saying strange things, Neville and Tonks privately wondered whether the blonde girl was quite right in the head.

The compartment drifted into an uneasy silence for a few minutes until Neville decided to speak.

"So, um, what do you teach, Tonks?" he asked.

"Science," Tonks answered promptly.

"Ah...good," Neville said lamely.

"I wish Professor Smith hadn't left," Luna said absently, taking the latest copy of The Quibbler out of her bag. "He was a good teacher. Us Ravenclaws treated him with a great deal of respect."

"Yeah, he was great," Neville agreed. "It would've been good if he were teaching again this year."

"Oi, I'm right here!" Tonks cried out in mock anger. Everyone chuckled.

"Mind you, where did he go?" Neville continued. "One minute, he's in the Hall, the next, he's disappeared into thin air!"

"I think he just wanted to get away," said Harry. "He doesn't really like being asked questions, and after everything that had happened, he was bound to be asked loads."

"Seems a bit strange, but then again everything about him _was_ strange," Neville laughed. "I mean, he could change his face, for Merlin's sake!"

Tonks thought back to several months ago, when Professor Smith had faced Voldemort. He had been at the receiving end of a killing curse, but miraculously, hadn't died. Instead, he'd exchanged a few words with Voldemort, then exploded in some sort of golden energy, which soon disappeared, revealing that his face had returned to what it had looked like when she first met him in Grimauld Place. She briefly wondered what kind of energy could have allowed such a transformation to take place. It certainly wasn't any energy familiar to muggles - perhaps he was an alien!

"He never looked any different to me," Luna said. "His appearance never changed at all."

* * *

The small talk continued for a couple of hours, before, around noon, Ron and Hermione finally entered the compartment.

"Wish the lunch trolley would hurry up, I'm starving," said Ron longingly, slumping into the seat beside Tonks and rubbing his stomach. "Hi, Neville, hi Luna. Guess what?" he added, looking at Harry. "Malfoy's not doing prefect duty. He's just sitting in his compartment with the other Slytherins, we saw him when we passed."

Tonks rolled her eyes. Ron had failed to notice her, even though she was sitting only a couple of centimetres away. Typical. Hermione, on the other hand, _had_ noticed her, and had given her a little wave and mouthed 'well done', before coughing when Ron stopped talking.

"Hem hem," she said. The sound jogged Tonks' memory; she remembered that some high-ranking member of the Ministry had used it quite often – Umbridge, that's right. The Senior Undersecretary to the Minister, who'd died at Hogwarts. Tonks frowned. She couldn't remember why.

"What?" asked Ron.

Hermione pointed at Tonks. Ron turned, and almost jumped out of his seat.

"Bloody hell, Tonks, you gave me a fright!" he said. "When did you get here?"

"I've been here all along, Mister Weasley," Tonks said wrily. "You just failed to notice me."

"Sorry," Ron said guiltily, before quickly turning back to re-engage Harry in a conversation about Malfoy.

Tonks sighed as Hermione sat down on her other side. "He's unbelievable, he is," she whispered. "I don't know how you put up with him."

"I don't know how either," said Hermione. "Sometimes he can just be so...infuriating!"

"I know what you mean. Charlie was much the same, but thankfully he pulled his head in in fifth year."

"I wish Ron would pull his head in," Hermione grumbled.

"Not likely," Tonks said. "By the way, that was a good Umbridge impersonation you did before. You almost passed for the real thing!"

Hermione frowned. "What do you mean. Who's Umbridge?"

Tonks stared at her. "No kidding, right? We had this conversation months ago, and you still don't remember her? After all she did?"

Hermione shook her head. "No, sorry. Should I?"

Tonks didn't reply, instead choosing to ponder why Hermione couldn't remember the horrid old witch who had terrorised Hogwarts' corridors for the majority of the school year. There was no possible cause that she could think of, unless Hermione was either lying, or unconsciously blocking all memory of her after experiencing a horrifying event that Umbridge instigated. Both possibilities were very unlikely, but Tonks was determined to find the cause of Hermione's apparent amnesia.

It never occurred to her that, conversely, Hermione was determined to find out why she _could_ remember Umbridge.

* * *

Several hours later, the train finally pulled into Hogsmeade station. Ron and Hermione bolted off to collect their luggage from the prefects' compartment, while Tonks kindly levitated down Luna and Neville's trunks for them, before doing the same to her own.

"Wonder where Harry is," Neville said worriedly. "He said he'd be back from Slughorn's compartment ages ago."

"He'll be fine, Neville," Tonks said reassuringly. "You go, I'll look for him."

She exited the train and dumped her luggage in the collection zone before walking to the station exit, scanning the crowd of students as they made their way to the thestral-drawn carriages. After several minutes, the last student had left the station – but she hadn't seen Harry. Anxiety filling her stomach, she rushed onto the platform and quickly scanned the train for anything conspicuous. A moment later, she spotted a carriage halfway down the train with all its blinds drawn. She immediately ran to the carriage, opened the door, and stepped inside. She walked down the carriage, looking everywhere for anything that would give Harry's presence away.

The train jolted and began to move, the motion causing her to lose her balance, and she stumbled forward, only to trip over an invisible object lying on the floor. She smiled. She knew exactly who she'd fallen over.

"Wotcher, Harry," she said, climbing to her feet and pulling the invisibility cloak off the unfortunate Gryffindor. A wave of her wand later and he was standing up, stretching furiously.

"Quick, we need to get off the train," Tonks said, and they both ran to the end of the carriage, and with only a moment's hesitation, jumped off and onto the platform. They stood still and caught their breath as they watched the train glide silently past the station and into the dark gloom beyond.

"Thanks," said Harry gratefully. "I thought I'd be on the train all the way back to London."

"Well, you're lucky you've got your resident Science Professor to watch your back," Tonks joked, before glancing at Hogwarts in the distance. The toll the castle had taken from the attacks earlier in the year were still visible. The astronomy tower was only partially rebuilt, and she was knew that a significant amount of roofing damage had yet to be repaired. "We'd better get back up to the school."

* * *

It took them ten minutes to make the long walk up to the castle. When they finally reached the entrance hall, they parted ways, Tonks entering the Great Hall via a rear entrance in the trophy room, while Harry slipped under the invisibility cloak and made his way to the Gryffindor table.

"Where have you been?" Professor Sinistra hissed as Tonks sat down next to her.

"Held up," Tonks said vaguely, and, not wanting to explain further, began eating the custard tart that had just appeared on her plate. Despite being a bit miffed that she'd missed out on the main course, she shrugged it off, making a mental note to nip down to the kitchens after the feast and get some food from the house elves.

Soon, the puddings too disappeared, and the loud mutterings from the students quickly ceased in anticipation of the Headmaster's speech.

"The very best of evenings to you!" Dumbledore said, smiling broadly, his arms opened wide as though to embrace the whole room.

The students gasped collectively; they had noticed his shrivelled, blackened right hand. Tonks was unperturbed (she'd known about the hand ever since an Order meeting a few weeks previously) but had to admit that the sight of it did make her feel a bit queasy every time she looked at it.

Dumbledore merely smiled and shook his purple and gold sleeve over his injury.

"Nothing to worry about," he said airily. "Now...to our new students, welcome; to our old students, welcome back! Another year full of magical education awaits you. Now, a few start-of-term notices. Firstly, Mr Filch, our caretaker, has asked me to say that there is a blanket ban on any joke items bought at the shop called Weasley's Wizard Wheezes. Those wishing to play for their house Quidditch team should give their names to their Heads of House as usual. We are also looking for new Quidditch commentators, who should do likewise.

"We are pleased to welcome two new members of staff this year. Firstly, Professor Slughorn."

Slughorn stood up, his bald head gleaming in the candlelight, his big waistcoated belly casting the table below into shadow.

"Professor Slughorn is a former colleague of mine, who has agreed to resume his old post of Potions master."

"Potions?"

"_Potions?_"

The word echoed all over the Hall as people wondered whether they had heard right.

"Professor Snape, meanwhile," said Dumbledore, raising his voice so that it carried over all the muttering, "will be taking over the position of Defence Against the Dark Arts teacher."

"No!" said Harry, so loudly that many heads turned in his direction. Tonks empathised with him. While not worried about the appointment, she knew that Harry and Snape disliked each other, and also, given Snape's...shady background, the fact that he was now teaching Defence would raise quite a few eyebrows. Still, it wasn't her concern, nor was it her place to be worried.

Dumbledore cleared his throat. The whole Hall had erupted in a buzz of conversation at the news that Snape had finally achieved his heart's desire.

"Secondly," Dumbledore said, loud enough to silence the mutterings. "Professor Tonks, who will be taking the now compulsory subject of Science."

Tonks grinned and waved as the students clapped rather tiredly.

"Now, as everybody in this Hall knows, Hogwarts was severely damaged after an attack by Lord Voldemort's forces earlier this year. It is for this reason that the West side of the Castle is out of bounds until such time that reconstruction has been completed." Dumbledore's blue eyes swept over the students before he smiled once more. "But now, your beds await, as warm and comfortable as you could possibly wish, and I know that your top priority is to be well-rested for your lessons tomorrow. Let us therefore say goodnight. Pip pip!"

With the usual deafening scraping noise, the benches were moved back and the hundreds of students began to file out of the Great Hall towards their dormitories. Tonks left the staff table and walked to the Gryffindor table, where Hermione and Ron were waiting for Harry to finish tying his shoe. She noticed that his nose now looked normal again; Hermione had probably fixed it.

"Why were you and Harry late?" Hermione demanded as soon as she noticed Tonks.

"He didn't get off the train; I had to go and find him," Tonks replied.

"What happened?"

Harry muttered something they couldn't make out.

"Well?"

Harry grimaced and spoke again. "I was spying on Malfoy," he said, "he noticed me, put me under a body-bind, trod on my nose and left me on the train."

Hermione just shook her head. "Oh, Harry," she sighed.

"What?" Harry protested. "I thought he was up to something!"

"This better not be about that theory of yours," Ron warned.

Seeing that the conversation was about to drift on to a topic that she wouldn't care about, Tonks bid the trio goodnight before hurrying down to the kitchens. The puddings hadn't filled her stomach, and there was still room for some more.

* * *

_She sitting at the staff table, listening to Professor Dumbledore as he addressed the students._

_"I never sent you a signal, but it's very splendid to see you. Have another cracker," he said, beaming._

_'_I don't mind if I do,_' Tonks thought as he reached for the packet of crackers in front of Professor Sinistra._

* * *

**Author Note: Now that we're finally at Hogwarts, the main plot of the story can finally get under way. That's not to say it hasn't been present in this chapters, or the three previous ones, it's more that, from now on, it will start to get more attention. There a little clues littered in chapters 1-4 that will be important to the story later on, so see if you can find them! Oh, and if you haven't realised, the italicised scenes at the end of a chapter are dream sequences.  
**

**Replies to reviews:**

**Mrs Dalek: Foreshadowing is cool! :) Tonks is certainly not all she seems, you're right there. No, unfortunately, she's not Susan (don't worry, I do know who Susan is!). I have written a story where the Doctor meets her again though, so you can check it out if you want. It needs to be improved a lot, though, it's pretty rushed.  
**

**Bright Eyes Illusionist: For the most part, the story will be told completely from Tonks' point of view, with the occasional scene or too from either the trio's or the Doctor's. Thanks! And tenses are difficult, aren't they? ;)**

**Wonderbee31: Uploaded? Interesting word choice there... All will be revealed, eventually!**

**Miyu Hinamori: That's the plan!**

**Nikki Pond: He'll be back, don't worry! Obviously, he wasn't back in this chapter, but he will be making an appearance in the not too distant future.**

**Insanityisgood25: While I don't feel your pain, I can definitely empathise with you! Unfortunately, though, I won't be telling anyone what the deal with Tonks is, you'll have to wait until the chapter with that revelation comes along! The Doctor will appear in either the next chapter or the one after, it depends how much last-minute editing I do before I publish the chapter. Thanks!**


	5. A Surprise Visitor

**Author Note: First of all, profuse apologies for being _this_ late in updating. Life got real busy a few weeks ago, and I haven't had spare time since. Thankfully, though, everything has finally died down, and I should be back on schedule, with chapter 6 being posted next week, just after the 50th Anniversary! So, I'm really sorry for taking so long to update, and I hope you enjoy the chapter!**

* * *

Chapter 5 - A Surprise Visitor

Tonks quickly settled into life at Hogwarts, though it felt more like she'd just come back from a holiday lasting several years. She'd forgotten what it was like to get up early and go for a jog around the Black Lake, before coming in for breakfast, eating, and heading off to class. The only things that were different were the facts that she never had to do homework as she was always marking it, and that she was teaching, not being taught. And how she loved it!

She had to admit that she'd had some lingering doubts about her ability to teach the students, but once she got going, she couldn't imagine how she'd ever been worried about it. Teaching the students was amazing; she got a thrill every time a class experienced a collective jaw drop, whether it had been caused by her telling the Fifth Years the basics of genetics, or informing the First Years that muggles had been to the Moon, or revealing the ins and outs of the different varieties of waves to the Sixth Years. She loved it.

Going by the students' reactions, they loved her too. Tonks' age and 'coolness' appealed to the student body, and she quickly gained the status of 'most popular teacher'. And it wasn't just her that was finding a special place within the students' hearts; her subject was as well. To Tonks' great surprise, she soon found that many students approached her after class to ask if there were any ways to research the topics they'd learnt further. She had been happy to oblige by explaining the subject in a greater depth than she had taught the class, but soon that was not enough, as the demand for further knowledge was too great. Finally, about a month after the start of term, she had spent a Saturday in the muggle world buying several science textbooks, which, upon her return to Hogwarts, she either put into the library (much to the annoyance of Madam Pince, who turned her nose at the textbooks, calling them 'inferior'), or kept them in her office.

As was to be expected, however, not everyone liked her and her subject. Initially, some of the Slytherins had hissed at her when they passed her in the corridors, or wondered out loud how her mother had married such muggle filth. Tonks was not easily beaten though, and several detentions later, the bullying had stopped, for the most part. Draco Malfoy, on the other hand, didn't stop. While he'd never insulted her family like his Housemates had (they were, after all, cousins), he found other ways to criticise her, saying that she sounded too much like Professor Smith, that he couldn't understand her, and that her purple hair was disgusting. Tonks, however, shrugged it off, and made sure that Malfoy had extra homework for a week.

All of this happened so rapidly that Tonks hadn't realised that she'd been teaching at Hogwarts for almost two months until someone had mentioned it in conversation. She'd been very surprised, she hadn't thought it had been _that_ long. Time flew when one was having fun, didn't it?

* * *

It was the 31st of October, and the whole school was eagerly anticipating the annual Halloween Feast. Well, everyone except Tonks, that is. For some reason, she'd never particularly liked the holiday, as she'd always been afraid of bats, vampires and the like, and Halloween delighted in celebrating those very monsters. It was annoying, and she'd once asked her parents why she was afraid of bats and other monsters, but all they could tell her was that she'd had a bad experience when she was younger. After trying unsuccessfully to remember what the experience was, Tonks had resigned herself to the fact that Halloween was not for her.

It was for this reason that, instead of helping the other teachers decorate the Hall for the occasion, Tonks could be found relaxing in the staffroom with Professor Sinistra. The two had got on very well from the start, and were on the way to becoming firm friends.

"Merlin, I love this job," Tonks said from couch by the fire. Sinistra was hunched over the long table, marking essays.

"You won't in a couple of years, mark my words," the Astronomy Professor remarked, dipping her quill into the ink pot. "You're teaching the same things over and over again to the same people for seven years. You'll hate it eventually."

"But that's just it, I won't be teaching the same thing over and over again," Tonks explained. "Science changes all the time, my curriculum will be different every year!"

"Suit yourself," Professor Sinistra shrugged. She would be proven right eventually.

"Your subject would be the same too, though," Tonks said thoughtfully. "I mean, new discoveries in astronomy are made all the time."

Sinistra shook her head. "Unfortunately, no. The last major discovery was made twenty years ago, shortly after latest model of charmed telescope came out. Apart from that, the only thing that's changed is the position of stars and planets, but even they repeat themselves eventually. I suppose you get the occasional meteor shower, but other than that, it's all the same."

"What?" said Tonks, surprised. "So you don't even know about the millions of galaxies beyond our own?"

Sinistra put down her quill and looked bemusedly at Tonks. "What do you mean, 'millions of galaxies'? Tonks, the only galaxy is ours!"

Tonks stared at her. "You're kidding, right? Tell me you're joking! Our galaxy is only one of billions in the entire universe!"

Sinistra laughed. "That's quite a thought, Tonks! But you can't expect me to believe you just because you say something. I need proof!"

"The Hubble Space Telescope," Tonks said immediately. "It's in Low Earth Orbit, and can take images with really high resolution, because the atmosphere's essentially non existant up there. Astronomers have counted sixteen hundred galaxies in just one photo!"

"Hubble Space Telescope – you're not talking about muggles, are you?" Sinistra scoffed. "What do they know about astronomy? They can barely tell the difference between the Sun and the Moon!"

Tonks' hair turned a fiery red – always a danger sign. "They know more about both than magical astronomers will ever know," she snapped. "You may be interested to learn that muggles know what the sun's made of, how it works, how far away it is, how long it takes light from it to reach us, how old it is, how much longer it's expected to live for and how hot it is! As for the moon, suffice to say that the muggles have been there – and more than once!"

Sinistra shook her head disbelievingly. "I'm sorry Tonks, but I can't believe that what you said is possible, let alone achievable by muggles."

"Fine!" Tonks said crossly, pushing herself out of the couch. "Fine. You want proof, you'll get it."

With that, she stormed out of the staffroom, leaving Sinistra to shake her head and return to marking essays.

* * *

Tonks walked down the second floor corridor fuming. She couldn't believe how closed-minded Professor Sinistra had been when it came to muggles and astronomy; she hadn't even entertained the thought that it was possible that they were further ahead in the field than wizards. Unfortunately, it seemed as if anti-muggle prejudice was everywhere. Hopefully, though, a few photos and facts from the textbooks she had bought a few weeks ago would convince her friend that she was right after all, but there was always the possibility that the astronomy teacher would reject the photos because they didn't move, and the facts as 'muggle nonsense'. It was unlikely, but that didn't stop the thought from niggling her mind. In fact, Tonks was so caught up in her thoughts that she never saw the man coming down the corridor, and only realised he existed when she bumped right into him.

"Ow!" she cried as her head impacted the man's rather prominent chin.

"Oh, sorry!" the man said quickly. "Didn't see you there, I was kinda...thinking...'bout stuff."

"Don't worry about it," Tonks mumbled, rubbing her forehead. "I was distracted too."

She looked up to see who she'd bumped into, and she froze. It was Professor Smith, the science teacher from last year, the one who had single handedly defeated Voldemort before disappearing not long after in his blue box! He'd come back! But why? He had told her, Ron, Hermione and Ron that he had no intention to come back. So why had he changed his mind?

"You!" she spluttered. "What're you doing here?"

"I'm sorry, have we met?" Professor Smith asked, looking down at her confusedly. "I'm a time traveller, I haven't met you in my future, have I?"

"I don't think so...you remember defeating Voldemort, don't you?" Tonks asked.

Professor Smith frowned. "Voldemort...oh, yes, him, I remember him. Typical megalomaniac, wanted world domination, unlimited power." He sniffed. "Nothing special. Why, were you there?"

"Of course I was bloody well there!" Tonks, offended. "You gave me your wand thing!"

Professor Smith blinked. "I did too; it's Tonks, isn't it? Hello! Sorry I didn't recognise you, it's been a few hundred years; I'm bound to forget a few things. Now, I'm looking for a girl called Clara Oswin, you wouldn't know her, would you?"

Tonks frowned. The name didn't ring any bells, and as she taught every single student in the school thanks to science being a compulsory subject, if a name wasn't familiar, that person wasn't at Hogwarts. "Sorry, no," she said. "She's not here."

At this, Professor Smith slapped his head. "Oh, of course, stupid Doctor," he moaned. "If you can remember me kicking out Mouldy-wart, Clara'll already be dead. Long story," he added, seeing Tonks' confused look. "I was trying to get here before she died, I wanted to ask her a few questions."

"Why would you want to speak to her if she's already dead?" Tonks asked, genuinely curious. It was quite a strange thing to do – unless, of course, he wanted to say sorry for her being dead. That made sense, but it was quite weird. Then again, 'weird' was essentially Professor Smith in a nutshell. He was a nice kind of weird, though, a genuinely nice guy. Not like that Xenophilius Lovegood , he was a strange weird, and freaked her out.

"Oh, you know, reasons," Professor Smith said evasively. "I'm just curious about her, that's all, but it seems like I've overshot a few years. I wonder if the Upsilon radiation around the castle's interfering with the helmic regulator, I'll have to check." He glared around at the brickwork, as if it was Hogwarts' fault that he'd gone further than intended.

"So, uh, what're you going to do now?"

Professor Smith shrugged. "I was thinking that I'd set up a sort of headquarters. Det Sen Monastery sounds good, I'll probably go there. Haven't been there for ages, actually, it's about time I popped in for a visit."

"What're you going to do there?"

"Oh, stuff..."

Tonks sighed, realising that Professor Smith wasn't going to say another else on the subject. Remembering that she was meant to be getting books to show Professor Sinistra that what she had said about muggles and astronomy was true, she tried to end the conversation.

"Well, it's been nice seeing you again, Professor, but I really must be going now, I'm rather busy at the moment."

Professor Smith nodded. "Yes, right, I should probably be off now too. Bye!"

"Bye." she replied, and began walking down the corridor, but it didn't take her long to realise that Professor Smith was following her. She stopped and turned to him. "Why are you following me?"

"I parked the TARDIS is classroom six, downstairs. Just habit, really."

"Oh...that's where I'm going too. I'm the new science teacher."

"Are you really?" Professor Smith said interestedly. "You explained Schrodinger's cat? What about quantum entanglement, are you familiar with that? Or the wave particle duality? Do you know why electrons have mass, or how..."

Tonks walked on in silence as Professor Smith rambled on and on about things that she should know, and if she didn't, she should learn straight away. He seemed so happy reeling off these scientific concepts (some of which she knew about, the rest she swore were made up) that she didn't want to interrupt him. Finally, just as her ears were starting to throb, they reached classroom six.

"...and the supermassive black hole at the centre of Mutter's Spiral, but I'm not sure that's a widely known fact at the moment, I'll have to check." Professor Smith finished.

Tonks groaned inwardly. "No, Professor, it's fine. I won't tell anyone, just in case."

"Well, that's alright then," Professor Smith said, walking into the room. "Now, I parked her somewhere here – oof!"

The outline of a box shimmered briefly before fading as Professor Smith rubbed his head. "Happens every time," he muttered crossly, before reaching into his pocket taking out a key, and trying to insert it into what Tonks could only assume was at the invisible keyhole to his box.

"How d'you make it invisible?" she asked interestedly. Wizards had been able to make objects invisible for decades, but as far as she knew, muggles had yet to find a way. She was interested to know what method Professor Smith – who was neither a wizard or (technically) a muggle – used.

"Oh, just using a bit of BTC – it makes the outer plasmic shell only reflect wavelengths of light outside the visible spectrum. Well, a human's visible spectrum. Some species would be able to see it right now."

"BTC?"

"Block transfer computation. It's basically what you lot use to conjure stuff. Speaking things into existence, that sort of thing. Except that making the TARDIS invisible isn't bringing it into existence. And no one's speaking..." He shook his head, dismissing the subject.

Tonks was intrigued. "What's happening then?"

Professor Smith grinned. "You're smart, Tonks, even by my standards, but I don't think you'd be able to cope with the concepts and engineering involved with a TARDIS. You're only human."

"Hmph," Tonks huffed, as Professor Smith finally found the keyhole, and the invisible door to the invisible box was soon opened.

"Well, goodbye...again," Professor Smith said, stepping inside the box. "It's been a pleasure seeing you again."

"Same," Tonks said, smiling. Professor Smith, despite his eccentricity, seemed like a really nice person, and she'd like to know him better. Unfortunately, though, it was evident that that wasn't going to be the case. "Will you be coming back again?" she asked.

"No, I don't think so," Professor Smith said. "Nothing else left here."

"That's what you said last time," Tonks reminded him pointedly.

"Yeah...well, stuff happens."

"Just say it, Professor."

"Fine. There's a possibility that I will be coming back, but it's very small, and don't spend the rest of your life hoping that it'll happen," Professor Smith grumbled. "There, happy?"

"For now," Tonks said, grinning mischievously. 'See ya."

Professor Smith saluted her, then disappeared inside the box, shutting the door behind him. A few seconds later, the familiar wheezing, groaning sound began. Although she couldn't see it, she knew that the box was fading from existence.

Suddenly, she felt a little dizzy. Steadying herself on a desk, she waiting for the sensation to pass. When it did, she couldn't help wondering why it had happened. She was pretty thirsty, she realised. When was the last time she had had a drink?

* * *

_She was walking through the Forbidden Forest with Professor Dumbledore, with only the light from their wands penetrating the dark gloom of midnight._

_"I'm very pleased with your performance so far, Nymphadora," Dumbledore said. "You and your subject are very popular with the students."_

_Trees rustled behind them, and she looked up in alarm._

_"Never mind," said Dumbledore, noticing her discomfort. "Bats; quite harmless."_

_A bat swooped down and bit the Headmaster on the neck._

_"Ow," Dumbledore cried, hand moving up to his neck to cover the wound. "Well, in theory. That one was a bit carnivorous."_

_She looked up at the sky nervously. It was filled with bats, all of which were diving towards her. She screamed as the surrounded her, their wings flapping against her body, their teeth tearing into her flesh. Still screaming, she started running as fast as she could, hoping that she would leave the bats behind._

oOo

Tonks woke, breathing heavily. Rolling her eyes at the memory of the dream, she close her eyes, rolled over and tried to get back to sleep.

'_Bloody Halloween,_' she thought fiercely. '_Gives you blo__ody nightmares_.'

As she drifted off into sleep once more, it never occured to her that that dream held the key to her phobia of bats.

* * *

**Author Note: Once again, I do apologise for this really late update, and I do hope it was good enough to make up for the long delay.  
**

**Another character driven chapter, but it sets stuff up, gives clues to the climax of the story, etc. The Doctor won't be back for quite a while now, but when he does return, he'll be staying for the rest of the story.**

**Also, I've seen the trailers for the 50th Anniversary, and they are awesome! And the minisode The Night of the Doctor was amazing; if you haven't seen it, go and watch it now! **

**Replies to Reviews:**

**Wonderbee31: Thanks! Basically, she only saw 11, even when 11 looked like 10 because of the time reversal. I hadn't thought of her seeing the TARDIS that way, but I imagine that she would. The main plotline of HBP will still occur, but obviously there will be differences. Only small ones this time, though, nothing like the ones Harry Potter and the Mystery of the Blue Box made.**

**Bright Eyes Illusionist: Thanks! I think that ability's cool too, it's just so Luna! Tonks is completely, 100% human, I'm afraid. Hope you liked the Doctor's appearance in this chapter!**

**Earl Annex: Jenny, the Doctor's 'daughter'? (There's a few Jennies in the Whoniverse!) I dunno, I like the character and would like her to return, but will only write for her if I come up with the right story. Thanks!**

**SuOmAlAiNeN92: There's a reason behind that decision...you'll find out why eventually! Thanks, and I'm not telling what that connection is! The Doctor in this chapter is between The Snowmen and The Bells of Saint John. There's a reference to Det-Sen Monastery, which is where he'll be going to (in this story) instead of the one in Cumbria in 1207. This is only because I like continuity references, and Det-Sen was visited by the 2nd Doctor. He also first faced the Great Intelligence there, so it seemed fitting.**

**Insanityisgood25: Luna knows something, you're right there. But what? Thanks! Regular updates? Oh yeah, totally. *cough cough* **


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